For months, U.S. commanders have been warning that even when the last bit of Syrian territory was liberated from the control of the Islamic State, the brutal ISIS movement would be far from defeated.

“Unrepentant, unbroken, and radicalized” is how Gen. Joseph Votel described what’s left of ISIS on March 7 in his final appearance before Congress, just three weeks prior to stepping down from commander of U.S. Central Command.